Thermal limiter constructions

ABSTRACT

A thermal limiter construction for at least one electrical circuit comprising a body member of electrical insulating material having a reduced portion projecting therefrom and adapted for insertion in an opening of a frame while the body member is adapted to abut one side of the frame outboard of the opening. A pair of leads are carried by the body member and project from the body member remote from the projecting portion thereof for lead attachment thereto. A thermally responsive fuse is carried by the reduced projecting portion and is interconnected in series with the leads. Either the body member or one of the leads has a single fastening opening passing therethrough adapted to fasten the body member to the frame solely by a single fastening member passing through the fastening opening when the projecting portion of the body member is inserted in the frame opening.

United States Patent 1191 Plasko et al.

[ Dec. 2, 1975 l l THERMAL LIMITER CONSTRUCTlONS (75] inventors: EmilRobert Plasko, Washington Township, Montgomery County; James Allen Kohl,Kettering; Michael Raymond Hutchison, Wayne Township, Montgomery County,all of Ohio Related US. Application Data {62] Division of Ser. No.335,9l l Feb 26, l973. Pat. No 3.839,693, which is a division of Ser.Nov l79.688 Sept. l3 l97l Pat. No. 3.73l.248.

[73] Assignee:

1521 11.5. c1. 337/208; 219/517; 337/201 1511 Int. Cl. H01H 84/48 [58)Field of Search 337/l86, 194. 201, 202,

337/208 2l6 225, 349; 219/517; 339/l26 R, 217, 2!) I, 219 R [56]References Cited UNITED STATES PATENTS 3,839,693 lO/l974 Plnsko 4.337/208 Primary ExaminerJ. D. Miller Assisranl Exarniner-Fred E. BellAttorney, Agent or Firm-Candor Candor & Tassone ABSTRACT A thermallimiter construction for at least one electrical circuit comprising abody member of electrical insulating material having a reduced portionprojecting therefrom and adapted for insertion in an opening of a framewhile the body member is adapted to abut one side of the frame outboardof the opening. A pair of leads are carried by the body member andproject from the body member remote from the projecting portion thereoffor lead attachment thereto. A thermally responsive fuse is carried bythe reduced projecting portion and is interconnected in series with theleads Either the body member or one of the leads has a single fasteningopening passing therethrough adapted to fasten the body member to theframe solely by a single fastening member passing through the fasteningopening when the projecting portion of the body member is inserted inthe frame opening 10 Claims, 9 Drawing Figures US. Patent Dec. 2, 1975Sheet 1 of2 3,924,217

U.S. Patent Dec. 2, I975 Sheet 2 of2 3,924,217

l8 and therein. Two like metallic relatively rigid leads 2] and 22 arepress-fitted through the slots 17 and 18 of the body member 11 so thatone set of ends 23 and 24 thereof project from the body member 1] remotefrom the cylindrical projection 12 for lead attachment purposes whilethe opposite ends 25 and 26 project outwardly as illustrated from thecylindrical projection 12. The metallic and conductive leads 21 and 22respectively have conventional tangs 27 formed thereon for securing thesame within the respective slots 17 and 18 of the body member 11 withoutauxillary fastening means.

A thermally responsive fuse 28 or other thermally re sponsive device iscarried by the projecting portion 12 of the body member 11 and hasopposed electrical leads 29 and 30 respectively electricallyinterconnected to the ends 25 and 26 of the rigid leads 21 and 22 in anysuitable manner, such as by soldering or the like whereby the thermallyresponsive fuse 28 is disposed in series with the rigid leads 21 and 22.The leads 29 and 30 of the fuse 28 are flexible, but rigid enough tohold the fuse 28 in its spaced relation from the body member 11 asillustrated. The thermally responsive fuse 28 can be of the thermallycollapsible pellet type as disclosed in the P. E. Merrill US. Pat. No.3,180,958 issued in April, 1965, with the result being that should thethermally responsive fuse 28 sense a temperature above a certaintemperature, the pellet therein will col lapse and cause electricaldisconnection between the leads 29 and 30 thereof and, thus, adisconnection be tween the leads 25 and 26 of the thermal limiterconstruction.

Since the internal workings and structure of the fuse 28 do not form thefeatures of this invention, further description thereof is unnecessaryas reference can be made to the aforementioned US. patent for any desired details thereof.

The triangular apex portion 31 of the body member 11 that extends beyondthe cylindrical portion 12 in offset relation relative thereto has asingle fastening opening 32 passing therethrough and through which athreaded bolt 33 can pass and through an aligned and cooperating opening34 in the frame 14 to be interconnected thereto by a nut 35 so as tofirmly fasten the thermal limiter construction 10 to the frame means 14by the single fastening member 33 because the same cooperates with therelatively large projecting portion 12 of body member 11 being receivedin the opening 13 of the frame 14 to withstand vibrations and shocks sothat the fuse 28 will remain in its proper location relative to theheater element 15 as illustrated.

Thus, it can be seen that the thermal limiter construction 10 of thisinvention can be simply and inexpensively fastened to the frame means 14by a single fastening member to control the electrical circuit 16 in amanner now to be described without requiring the multiple fasteningarrangements as utilized in the past.

One end 36 of the electrical heater element 15 is fastened to the frame14 by a terminal post arrangement 37 that includes a threaded fasteningmember 38 passing through opening 39 in the frame 14 and being insulatedfrom the frame 14 by an insulating bushing 40 that has part thereof alsodisposed in the frame opening in a conventional manner. The end 23 ofthe terminal 21 of the thermal limiter construction 10 of this inventionis adapted to be electrically interconnected to the threaded fasteningmember 38 of the heater 15 by an electrical lead 41, the lead 41 beingsoldered respec- 4 tively to the fastening member 38 and lead 21 orfastened thereto in any other desired manner.

The other end 42 of the electrical heater element 15 is adapted to beinterconnected to a power source lead L in any suitable manner, such asby a lead 43 as illustrated in FIG. 1. Similarly, the end 24 of the lead22 of the thermal limiter construction 10 of this invention is adaptedto be interconnected to the other power source lead L in any suitablemanner, such as by lead 44 as illustrated in FIG. 1.

Thus, it can be seen that the thermally responsive fuse 28 of thethermal limiter construction 10 is now disposed in series with theelectrical heater element 15 across the power source leads L, and Lwhereby should during the operation of the electrical heater 15, whenconventional on-off switch means 45 and 46 in the leads 43 and 44 aredisposed in closed positions thereof, the output temperature effect ofthe element 15 as sensed by the thermally responsive fuse 28 exceed acertain high limit safe value or limit that is usually a value higherthan that attempted to be maintained by the usual electrically operatedthermostatic control means 47 that controls the circuit means 16, thefuse 28 will blow in the manner set forth in the aforementioned US.patent and thereby terminate the flow of electrical current through theheater element 15 and maintain such circuit open condition until thethermal limiter 10 is replaced.

However, since the thermal limiter construction 10 of this invention ismounted to the frame 14 by only a single fastening member, thereplacement of a blown thermal limiter construction 10 of this inventionis a relatively simple matter, because once the same is mounted in placeby the single fastening member 33, the lead ends 23 and 24 can berespectively coupled into the circuit 16 in the manner previouslydescribed by the lead means 41 and 44.

Therefore, it can be seen that the thermal limiter construction 10 ofthis invention can be firmly mounted in place on the frame means 14 tocontrol the electrical circuit 16 in an effective and efficient mannerby merely having a single fastening member 33 utilized for the fasteningarrangement because the relatively long projecting portion 12 of thebody member 11 will not jar out of its frame opening 13 during adversevibrations and shocks, imposed against the frame 14 as normallyencountered during transportation etc. of the unit 16.

Another thermal limiter construction of this invention is generallyindicated by the reference numeral 10A and is utilized in an electricalcontrol system 16A, the parts of the thermal limiter construction 10Aand the electrical system 16A that are the same as the thermal limiterconstruction 10 and circuit 16 of FIGS. 1-3 are indicated by likereference numerals followed by the reference letter A.

As illustrated in FIG. 4, the thermal limiter construction 10A issubstantially identical to the thermal limiter construction 10previously described except that the rigid lead 21 has been replaced bya rigid lead 48 that is mounted in the body member 11A in the samemanner as the lead 22A but has an end 49 bent at right angles relativethereto with the bent part having an opening 50 passing therethrough toreceive the threaded fastening member 38A for the heating element 15Awhen the projecting portion 12A of the body member 11A is fully receivedthrough the opening 13A in the frame 14A as illustrated so as to besecured to the threaded fastening member 38A by another nut 51sandwiching the free end 49 of the lead 48 between the nut 51 and theoriginal mounting nut for the bushing 40A. In this manner, not only doesthe lead 49 electrically interconnect the thermal limiter construction Ain series with the heater element A for the purpose previously described, but also such lead 49 and its single opening 50 can be utilizedas the sole means for fastening the thermal limiter construction 10A tothe frame means 14A as it is not necessary to utilize a fastening memberin the opening 32A of the body member llA. Of course, the opening 32A inthe body member 11A could be utilized in addition to the fasteningopening 50 of the lead 48, if desired, However, because of therelatively long projecting portion 12A of the body member 11A beingreceived in the frame opening 13A, the securement of the lead 48 to thepost 38A is sufficient to hold the thermal limiter construction 10A tothe frame 14A without having the same shake loose during subsequentvibrations and shocks imposed on the frame 14A.

Another thermal limiter construction of this invention is generallyindicated by the reference numeral 108 and is utilized in an electricalcontrol system 168, the parts of the thermal limiter construction 10Band circuit 16B similar to the construction 10 or 10A and circuit 16 or16A are provided with like reference numerals followed by the referenceletter B As illustrated in FIG. 5, the thermal limiter construction 108is formed in substantially the same manner as the thermal limiterconstruction 10A except that the lead 22A has been replaced by anotherlead 52 of this invention which is fastened in the body member 113 inthe same manner the lead 22A but has a straight end 53 projecting out ofthe slot i815 and is provided with a threaded opening 54 passingtherethrough and to which a bus bar type lead 55 can be fastened by athreaded fastening member 56 passing through a selected opening 57 inthe bus bar lead 55 and into the threaded opening 54 of the lead 52 soas to interconnect a plurality of thermal limiter constructions lOB inparallel or in series with one another, if desired, while the same aremounted to the frame [4B in the same manner.

in any event, it can be seen that the thermal limiter construction 10Bof this invention is adapted to be fastened to the frame means l' lB bythe single fastening opening 5013 in the lead 43B- thcreof in the mannerprcviously described for the thermal limiter construction 10A.

Since the lliCl'D'lFll limiter constructions 10A and 10B are adapted tobe mounted respectively to the frame means 14A and 148 by the singleopenings 56 and 503 in the leads 48 and 48% thereof, the triangularportion 3! of the body member ill could be eliminated since the opening34 thereof is not being utilized for such 5 mounting purposes, unlessdesired,

Therefore, another thermal limiter construction 10C of this invention isillruztrated in FIGS. 6 and 7 for controlling an electrical circuitmeans 16C in the same manner as th constructions lilit and 10Bpreviously described so that liar parts are indicated by like refer encenumerals followed by the reference letter C.

As illustrated in llt rli. ti and 7, the body member 3 it. of thehcrnzui limiter ct instruction 10C is formed ill a larger cylin jiricals opt: than the projecting cylindri al poi lion 12m thereof Wl'lllt.being concentric therewith so as to abut against the side of the framemeans Mil outboard of the opening MC passing therethrough while theopening C through the lead 48C thereof is being utilized as the solemeans for mounting the body member 11C to the frame means 14C at theterminal post 37C in the manner previously described.

While the thermally responsive element or fuse 28 for the variousthermal limiter constructions 10 of this invention have been illustratedas being located in one position relative to the projecting portion 12thereof, it is to be understood that the thermally responsive fuse 28could be disposed in other positions, as desired.

For example, reference is now made to FIG. 9 wherein another thermallimiter construction of this invention is generally indicated by thereference numeral 10D and parts thereof similar to the thermal limiterconstruction 10 of this invention are indicated by like referencenumerals followed by the reference letter As illustrated in FIG, 9. thethermally responsive fuse 28B is mounted in substantially a verticalfashion relative to the lead 21D while the leads 29D and 30D thereofrespectively electrically interconnect the opposed electrical sides ofthe fuse 28D to the leads 21D and 22!), as illustrated, whereby the fuse28D functions in the manner previously described.

Therefore, it can be seen that in all of the embodiments of thisinvention the thermal limiter construction is adapted to be mounted to asupporting frame by a single fastening member passing through a singlefastening opening of the thermal limiter construction, such openingbeing formed either in the body member of the thermal limiterconstruction or through a rigid lead means thereof,

While the form of the invention now preferred has been disclosed asrequired by the patent statute, other forms can be utilized. all comingwithin the scope of the appended claims.

What is claimed is:

l. A thermal limiter construction for at least one electrical circuitcomprising a body member formed of electrical insulating material andhaving a relatively long reduced portion projecting therefrom adaptedfor insertion in an opening of a frame while said body member is adaptedto abut one side of said frame outboard of said frame opening, said longreduced projecting portion having a longitudinal axis, a pair of leadmeans carried by said construction for lead attachment thereto, and athermally responsive device carried by said reduced portion and beinginterconnected in series with said lead means, one of said lead means ofsaid construction having a single fastening opening passing therethroughand being adapted to fasten said body member to said frame by a singlefastening member passing through said fastening opening when saidprojecting portion of said body member is fully inserted in said frameopening, said fastening opening passing through said one lead means inoffset relation to said projecting portion thereof and beingsubstantially parallel to said longitudinal axis of said projectingportion whereby said fastening member and said reduced projectingportion are adapted to cooperate to prevent piv- Sling of saidprojecting portion out of said frame openmg A thermal limiterconstruction as set forth in claim i wherein said body member has agenerally cylindrical -':onliguration.

3. h tl'icrrnal limiter construction as set forth in claim 2 whereinsaid projecting portion of said body member also has a generallycylindrical configuration that is smaller in diameter than the diameterof said body member.

4. A thermal limiter construction as set forth in claim 1 wherein saidthermally responsive device comprises a fuse element.

5. A thermal limiter construction as set forth in claim 1 wherein saidprojecting portion of said body member has a generally cylindricalconfiguration.

6. In combination, a frame having an opening passing therethrough anddefining an internal peripheral surface of said frame, an electricalheater element carried by said frame, a thermal limiter constructioncomprising a body member formed of electrical insulating material andhaving a relatively long reduced portion projecting therefrom into saidopening of said frame while said body member abuts one side of saidframe outboard of said frame opening, said reduced projecting portionhaving an external peripheral surface disposed closely adjacent saidinternal peripheral surface of said frame, said reduced projectingportion having a longitudinal axis, a pair of lead means carried by saidconstruction for lead attachment thereto, one of said lead means beingelectrically interconnected in series with one end of said heaterelement, a thermally responsive device carried by said reduced portionof said body member and being interconnected in series with said leadmeans and, thus, in series with said heater element, said one lead meansof said construction having a single fastening opening passingtherethrough in offset relation to said projecting portion thereof andsubstantially parallel to said longitudinal axis of said projectingportion, and a fastening member fastening said body member to said frameby passing through said fastening opening and being secured to saidframe for holding said projecting portion of said body member fullyinserted in said frame opening whereby said fas tening member and saidreduced projecting portion cooperate to prevent pivoting of saidprojecting portion out of said frame opening.

7. A combination as set forth in claim 6 wherein said body member has agenerally cylindrical configuration.

8. A combination as set forth in claim 7 wherein said projecting portionof said body member also has a generally cylindrical configuration thatis smaller in diameter than the diameter of said body member and saidframe opening is circular.

9. A combination as set forth in claim 6 wherein said thermallyresponsive device comprises a fuse element.

10. A combination as set forth in claim 6 wherein said projectingportion of said body member has a generally cylindrical configurationand said frame opening is circular.

3,924 ,217 Dated December 2 1975 Patent No.

Emil Robert Plasko et a1. Inventor(s) It is certified that error appearsin the above-identified patent and that said Letters Patent are herebycorrected as shown below:

The term of this patent subsequent to May 1, 1990, has been disclaimed.

Signed and Scaled this s th [st-nu.) D f July 1976 Arrest:

RUTH C. MA SON C. MARSHALL DANN Anestmg ()ffwe! (ummissmner njlarenrsand Trademarks

1. A thermal limiter construction for at least one electrical circuitcomprising a body member formed of electrical insulating material andhaving a relatively long reduced portion projecting therefrom adaptedfor insertion in an opening of a frame while said body member is adaptedto abut one side of said frame outboard of said frame opening, said longreduced projecting portion having a longitudinal axis, a pair of leadmeans carried by said construction for lead attachment thereto, and athermally responsive device carried by said reduced portion and beinginterconnected in series with said lead means, one of said lead means ofsaid construction having a single fastening opening passing therethroughand being adapted to fasten said body member to said frame by a singlefastening member passing through said fastening opening when saidprojecting portion of said body member is fully inserted in said frameopening, said fastening opening passing through said one lead means inoffset relation to said projecting portion thereof and beingsubstantially parallel to said longitudinal axis of said projectingportion whereby said fastening member and said reduced projectingportion are adapted to cooperate to prevent pivoting of said projectingportion out of said frame opening.
 2. A thermal limiter construction asset forth in claim 1 wherein said body member has a generallycylindrical configuration.
 3. A thermal limiter construction as setforth in claim 2 wherein said projecting portion of said body memberalso has a generally cylindrical configuration that is smaller indiameter than the diameter of said body member.
 4. A thermal limiterconstruction as set forth in claim 1 wherein said thermally responsivedevice comprises a fuse element.
 5. A thermal limiter construction asset forth in claim 1 wherein said projecting portion of said body memberhas a generally cylindrical configuration.
 6. In combination, a framehaving an opening passing therethrough and defining an internalperipheral surface of said frame, an electrical heater element carriedby said frame, a thermal limiter construction comprising a body memberformed of electrical insulating material and having a relatively longreduced portion projecting therefrom into said opening of said framewhile said body member abuts one side of said frame outboard of saidframe opening, said reduced projecting portion having an externalperipheral surface disposed closely adjacent said internal peripheralsurface of said frame, said reduced projecting portion having alongitudinal axis, a pair of lead means carried by said construction forlead attachment thereto, one of said lead means being electricallyinterconnected in series with one end of said heater element, athermally responsive device carried by said reduced portion of said bodymember and being interconnected in series with said lead means and,thus, in series with said heater element, said one lead means of saidconstruction having a single fastening opening passing therethrough inoffset relation to said projecting portion thereof and substantiallyparallel to said longitudinal axis of said projecting portion, and afastening member fastening said body member to said frame by passingthrough said fastening opening and being secured to said frame forholding said projecting portion of said body member fully inserted insaid frame opening whereby said fastening member and said reducedprojecting portion cooperate to prevent pivoting of said projectingportion out of said frame opening.
 7. A combination as set forth inclaim 6 wherein said body member has a generally cylindricalconfiguration.
 8. A combination as set forth in claim 7 wherein saidprojecting portion of said body member also has a generally cylindricalconfiguration that is smaller in diameter than the diameter of said bodymember and said frame opening is circular.
 9. A combination as set forthin claim 6 wherein said thermally responsive device comprises a fuseelement.
 10. A combination as set forth in claim 6 wherein saidprojecting portion of said body member has a generally cylindricalconfiguration and said frame opening is circular.